The 56-year-old actor canceled an appearance at Calgary Expo on April 2 "due to unforeseen circumstances in his schedule," according to the event's Twitter account, but there were no further details.

Whoa! This is heavy. Michael J Fox is not able to be with us at #CalgaryExpo. We received the following message from his publicist to share with you all - “Due to unforeseen circumstances in his schedule Michael J. Fox is not available to attend.” (1/2) pic.twitter.com/WaBJ4BUluN

Fox rose to fame for his roles in the sitcom "Family Ties" and films "Teen Wolf" and "Back to the Future." After being diagnosed with the neurological condition in the early 1990s, he continued working, mostly in television, including "Spin City," "The Good Wife" and a recent guest starring apperance in "Designated Survivor."

He has been a leading advocate for Parkinson's research and people living with the disease.

Getty ImagesJohn Lamparski/WireImage via Getty

Tracy Pollan and Michael J. Fox attend 2017 Can-Do Awards at Cipriani Wall Street on April 19, 2017 in New York City.